Manual sanding tools are well known in the art. These tools typically comprise a body to which is affixed a sheet of abrasive material such as sandpaper or emery cloth. The tool is then grasped in the hand, or by a handle, and used to perform the desired sanding operation. For example, U.S. Pat. No. 1,927,574 shows a holder for sandpaper, emery cloth and the like for use in the cleaning of eggs and for wood polishing. A sheet of abrading material is stretched over a concave undersurface, and is held in place by a pin and slot arrangement. A layer of rubber, felt, or other suitable resilient or yieldable material is glued to the concave undersurface. U.S. Pat. No. 2,402,069 illustrates an abrading and polishing tool whose operative faces follow the contour of the surface against which they are applied. The tool consists of a frame of articulated construction, having for a basic element a cushion consisting of a fluid containing pad whose flexibility, combined with the responsiveness of the frame, permits the surface of the cushion, under pressure imposed on the frame, to conform to the contour of the surface being abraded or polished. U.S. Pat. No. 2,546,245 defines a sander wherein the bottom plate may be shaped in a manner to conform closely to the shape of the work which is being sanded. The sander includes a sheet-metal body having a pair of parallel inverted U-shaped jaws within which a pair of upwardly convergent flanges carried by a bottom plate are adapted to be engaged, with the flanges having means at each end thereof to hold the bottom plate against endwise movement. U.S. Pat. No. 2,817,931 discloses a dry wall angle sander for sanding the corners and angles of a plaster and like wall to make the wall angle clear and clean and particularly free from irregularities. The sander has a means for gripping emery cloth and sandpaper in a renewable condition so that the sander may be sharp and capable of perfect operation at all times. The gripping means includes two split tubes. U.S. Pat. No. 3,279,130 portrays a corner sander which is adapted to conform to and follow a corner wall portion when moved over large distances. The sander is in the form of an integral plate structure including two outside surfaces at an angle of substantially 270 with respect to each other. The apex portion of the surfaces is defined by a protuberance substantially bisecting this outward angle. This protuberance extends over the length of the outer surfaces and serves to engage the corner line of a wall corner when sandpaper is wrapped around the integral plate structure. Two clamping member secure the sandpaper to the sander. U.S. Pat. No. 4,774,789 comprises a corner sander having a sanding shoe of two angled plates. The plates from an integral angle in order to sand or abrade an external angle. The sanding shoe has a suitable mounting bracket to secure the shoe to a motor unit in a convenient manner for reciprocating the sanding shoe.
One particular sanding operation has special demands, which cannot be accommodated by the aforestated prior art sanding devices. In the wallboard construction industry for new homes, it is becoming evermore popular to fabricate 90.degree. outside corners. These outside corners are not covered by paper tape and filler as are the joints between two planar sheets of wallboard. Rather, the outside corners are connected by a metal strip called a bullnose cornerbead. The bullnose cornerbead is nailed or screwed into position outside the perpendicular wallboard sheets and then the two planar strip portions are covered with a coating of wallboard filler. The proper sanding of the filled bullnose cornerbead is difficult because the sanding operation should fully expose the central rounded portion of the bullnose cornerbead, while not gouging the filler which covers the two outside planar strip portions. A flat sander has proven ineffective in this task since all of the sanding force is concentrated along a narrow strip of the bullnose, oftentimes exposing the metal. For this reason, hand sanding with a palm-held sanding sheet is the most common method of sanding a bullnose. Even so, it is very easy to apply too much pressure at one point and gouge the filler.